Bingo! How to post to Lemmy from Mastodon!
Put the title of the post in the first line (or at least before any other IDs/users/groups). Then tag the lemmy community as though they are an account.
Then tag other people at the end if you want them included.
@test @paulschoe @piratepost @fediversenews @alghost
To tag a community, use the same format as with normal mastodon accounts, but use the name of the community. In this thread the community name is simply “test”.
You can find the name in lemmy by looking for “!test” format or look at the URL where it will be the part after the “/c/“: https://lemmy.ml/c/test/data_type/Post/sort/New/page/1
Then the second part is the domain of the instance. That is, here, lemmy.ml.
Mastodons search should help find these communities